1. Field of the Invention
The present invention relates to a projection apparatus.
2. Description of the Related Art
Projection apparatuses include a projector using a semiconductor laser as a light source. If laser light is projected as it is in such a projector, diffraction fringes attributed to diffraction phenomena are generated because of the coherent characteristics of the laser light, or since the laser light is reflected by minute projections and depressions on a projection surface, interference and generate speckles are caused. Such diffraction fringes and speckles considerably deteriorate the quality of projected images.
According to known techniques for reducing diffraction fringes and speckles, laser light is converted into incoherent light by rotating a diffuser plate as shown in Jpn. Pat. Appln. KOKAI Publication No. 6-208089 or by vibrating the diffuser plate as shown in Japanese Patent No. 4682528.
However, when the rotary diffuser plate is disposed on the optical path of the laser as in Jpn. Pat. Appln. KOKAI Publication No. 6-208089, a part of the diffuser plate is only used, and the other part is not used, so that a wasteful mounting volume is taken up. When an actuator to drive the diffuser plate uses electromagnetic force as in Jpn. Pat. Appln. KOKAI Publication No. 6-208089 and Japanese Patent No. 4682528, the increase of power consumption for current driving is a problem.